Process of extracting acetic acid from alkaline acetates.



N0. 634,27l. Patented Oct. 3, I899.

H PLATEB-SYBEBG. PROCESS OF EXTRAGTING ADETIO ACID FROM ALKALINEAGETATES.

(Application filed Jan. 21, 1898.)

(No Model.)

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UNITED STATES.

, PATENT Erica.

PROCESS OF EXTRACTING ACETIC ACID FROM ALKALINE ACETATES.

SPECIFICATION forming part of Letters Patent No. 634,271, dated October3, 1899.

Application filed January 21, 1898.

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Be it known that I, HENRI PLATER-SYBERG, a subject ofthe Emperor ofRussia, residing at 81 Rue de la Boetie, Paris, France, haveinvented anew Process of Extracting Acetic Acid from Alkaline Acetates, of whichthe following is a specification.

My invention'consists in a process for extracting acetic acid fromalkaline acetates based upon the employment as primary material of thewood and mosses found in considerable quantities in the bogs or fens ofRussia and Lithuania and of other analogous materials rich incarbohydrates found in abundance in nature, and hence cheap. Thetreatment to which I submit these materials in order to obtain aceticacid in the form of an alkaline s'alt -onsists in submitting them to thesimultaneous action of a highly-concen trated alkaline lye and to thatof an oxidizing agent, which may be the oxygen of the air. I thus obtaineven by a cold process, but still more rapidly by a hot process, veryconsiderable quantities of alkaline acetate.

The following is a mode of carrying out the invention: The wood, reducedto chips in order to present as large a surface for attack as possible,or the moss is thrown into the boilers containingthe highly-concentratedalkaline lye, (by preference potash lye,) and I then boil in thepresence of an oxidizing agent, which may be the oxygen of the air. Forthis purpose the air may be continuously injected into the liquid mass.The temperature of boiling varies according to the concentration of thelye. It must not go beyond 130 centigrade if it be desired to avoid theformation of an alkaline oxalate and to obtain a maximum of acetic acidin the form of an alkaline acetate. The alkaline acetate having beenthus obtained the acetic acid has next to be separated therefrom.

The usual. process hitherto for separating acetic acid from its salinecombinations consists in treating the latter with a mineral acid whichdisplaces the acetic acid,while saturating the base wherewith it isunited; but this process has the inconvenience of destroying almostentirely the value of the mineral acid employed and that of the base,while forming residuals that are difficult to utilize. In order to avoidthese inconveniences, I first Serial No. (567)492. (N0 specimens.)

electrolytically separate the acetic acid from the alkaline base, whilecontriving-to obtain the latter in the free state and the acetic acid inthe form of a soluble salt. For this purpose I operatecold in anelectrolytical cell, such as is represented in the accompanying drawing,which represents it in perspective and partly in section. This cell isdivided by a porous diaphragm ab into two compart ments, in one of whichis placed the anode c and in the other the cathode d. The porousdiaphragm may be of anymaterial which fulfils the following conditions,viz: It should be capable of resisting the destructive action of thesolutions employed, should offer very slight resistance to the passageof the current, and should offer sufficient resistance to the passage ofthe solutions in the two compartments to-prevent their mixture. The saiddiaphragm is represented in the drawing as formed of two perforatedsheet-iron plates at, having between them a space which is filledwithtightly-compressedamianthusfiberb. If the plates at be of iron, anytendency to their action as bipolar electrodes may be counteracted bycoating them with a siccative solution of resin or caoutchouc. In mypractice, however, with bare iron plates such tendency has been veryfeeble and has not manifested itself to suchcxtent as to interfere withthe process.

The anode c is of iron. It is represented as composed of brokencast-iron oriron shavings or chips. yet it may be of copper. That faceof the diaphragm which is next the anode-compartment of the cell, aswell as the walls and bottom of said compartment, are lined withinsulating material 6.

The anode solution should at the first consist of water slightlyacidulated with acetic acid, to which for the purpose of diminishing theresistance there may be added a little alkaline acetate or acetate ofiron, but the reaction should be always freely acid around the anode.

The cathode solution to be decomposed is of alkaline acetatepotassicacetate, for example-which may be at the first either of alkaline orneutral reaction; but after afew minutes operation this solution becomesalkaline, and its alkalinity increases as the op- The cathode may alsobe of iron,

eration proceeds until there remains nothing but potash lye completelydeprived of acetic acid. Under these conditions after the pas sage ofthe current the alkaline acetate is decomposed and the acetic acidattacks the iron of the positive electrode to form ferrous acetate,while the base gathers around the negative electrode and may serve fordecomposing fresh quantities of wood or moss. The reactions may beexpressed by the following formulze Electrolytic decomposition:

C U O K C H O K. The anode reaction:

2(O H O )+Fe:(C II OQ Fe. The cathode reaction:

K-l-ILO KOII-l-II.

The ferrous acetate obtained as above described is pulverized in contactwith the air and forms itself into ferric acetate. To this ferricacetate is added a suitable quantity of neutral acetate of potash, and Ithen heat till it boils. Alittle before this moment a doubledecomposition takes place, the neutral acetate of potash beingtransformed into biacetate of potash, While the iron is all precipitatedin the form of hydrate of sesquioxid of iron. The biacetate of potashthus obtained is then submitted to the action of heat and separatesintoacetic acid and neutral acetate of potash, which serves to decomposefresh quantities of ferric acetate. Thus while operating in this mannerthe same caustic potash may theoretically serve ad mfimtum to transformwood or moss, only a certain quantity of iron has to be spent, whichpasses from the metallic state into that of an iron hydrate, and thenecessary force for engenderingthe necessary electric current for theelectrolytic operation is a relatively small matter.

I have stated above that an iron electrode has to be employed as theanode in this operation; but the iron might be replaced by another metalforming with acetic acid a soluble acetate, (such as zinc or lead, forinstance.) Iron is, however, preferable not only because of itscheapness, but also because the iron'salt is more suitable for thereactions named than the salts of zinc or lead.

I claim The process for extracting acetic acid from an alkaline acetateconsisting in first separating the acetic acid from the alkali byelectrolysis cold in a trough provided with a positive electrode of ironor other equivalent metal and having the two electrodes separated by aporous partition, then in transforming the ferrous acetate thus formedinto a ferric acetate by oxidizing with air, next in acting under theinfluence of heat upon this ferric acetate with neutral acetate ofpotash, and

finally in decomposing by heat the biacetate thus obtained into aceticacid and neutral acetate of potash, substantially as set forth.

In testimony that I claim the foregoing as my invention I have signed myname, in presence of two witnesses, this 8th day of January, 1898.

HENRI PLATER-SYBERG.

\Vitnesses:

F. DE TCHIHA'ECHE'I, PHILIP T. RIDDET'I.

